Step-by-step explanation:
According to the search results, the percentage of national output sold to consumers or households is approximately 68.4% [1]. This is based on the pie chart that shows the percentage of components of US GDP on the demand side, where consumption is 68.4% [1]. Additionally, the largest component of GDP is consumption expenditure by households, accounting for more than two-thirds of the GDP in any year[2]. However, it is important to note that GDP measures all output generated within the borders of a country, including goods and services produced for sale in the market and some nonmarket production such as defense or education services provided by the government[3]. Therefore, the percentage of national output sold to consumers or households may not be the same as the percentage of GDP accounted for by consumption expenditure by households.